Field of the Invention
The invention relates to a method for producing a casting provided with readable information.
Description of Related Art
Here, the castings produced according to the invention include components commonly produced by casting which are completely solidified and have been removed from the mould. Castings of the type produced according to the invention are therefore free of the mould parts required to cast them, such as risers, gates, inlets, seams and suchlike, as are usually removed after solidification by a subsequent processing step which in the technical language is also called “fettling”.
The castings produced according to the invention in particular are components for producing internal combustion engines. Therefore, cylinder heads and crankcases specifically designed for internal combustion engines are among the castings produced according to the invention.
Increasingly higher requirements are imposed on the quality of work pieces of the type in question here which are highly stressed in practical use. This relates both to their mechanical properties and to their dimensional stability. Since the quality of a casting is critically influenced by the production process, it is therefore increasingly more important to keep track of the different process steps undergone during the production of cast work pieces and assign them to the respective cast part. Here, full knowledge and traceability of all determining factors which are critical in the production process and which could have an effect on the quality or performance characteristics of the respective cast product is sought. Such traceability of production data individually assigned to each casting allows determined production deficiencies to be learnt from and corresponding corrections to the production process to be carried out. In this way, the process can be continually optimised.
In this respect, important production data are, for example, the production date, pouring rate, casting temperatures, type of production plant etc.
One way known from the prior art of attaching information with the required depth of detail to the casting necessary to uniquely individualise the respective casting entails providing a foundry core, which is used in a casting mould for casting cavities, channels or the outer contour of the casting, with a negative image of a unique character string by means of a laser, this unique character string being reproduced on the casting body in the course of the casting process and being visible after casting.
Information reproduced on the casting can be captured in the casting process using an automatically operating device, as for example described in JP 04 075761.
A simple way of identifying a casting is proposed in EP 0 363 791 B1, in which directly after casting a tag containing information about the respective casting is placed on the surface of the melt which is still free-flowing such that it floats there and protrusions on it reach into the melt. After solidification, the tag then adheres tightly to the obtained casting. However, for this procedure a larger surface section of the melt poured into the casting mould has to be freely available. This requires an open casting mould, which with many modern casting processes is not possible.
In order to solve this problem, in EP 2 196 272 B1 it was proposed to prefabricate a code carrier serving as an identification element and then moulded this code carrier with at least one section into the riser or another mould part of the casting blank obtained after solidification and removal from the mould. In this way, the code carrier is inseparably joined to the casting blank. The information contained on it can be easily captured and for example in a data processing device automatically assigned to the respective casting. However, the unique identification of the casting blank made possible by the code carrier is lost again when, in the course of fettling, those mould parts—and with them the code carrier attached to one of them—which although they are required for casting are not required as functional parts of the finished casting are separated from the casting.